function addLoadEvent(func) {
	var oldonload = window.onload;
	if (typeof window.onload != 'function') {
		window.onload = func;
	} else {
		window.onload = function() {
			if (oldonload) {
				oldonload();
			}
			func();
		}
	}
}

// form feedback upon submission
function showFormProcessingCue(){
	document.getElementById("submit_form").disabled = true;
	document.getElementById("form_processing_cue").style.display = "block";
	if( document.getElementById('login_response_success') )
		document.getElementById("login_response_success").style.display = "none";
	else if( document.getElementById('login_response_error') )
		document.getElementById("login_response_error").style.display = "none";
	else if( document.getElementById('login_response_cookies') )
		document.getElementById("login_response_cookies").style.display = "none";
}

// Unobtrusive JS initialization of form cue
function prepareFormCue(){
	if( document.getElementById && document.getElementsByTagName ){
		if( document.getElementsByTagName('form') ){
			var forms = document.getElementsByTagName('form'); 
			for (var i=0; i < forms.length; i++) { 
				var form_target = forms[i]; 	
					form_target.onsubmit = function(){ showFormProcessingCue(); }
			}
		}		
	}
}
addLoadEvent( prepareFormCue );